I think something that people haven’t mentioned is inflation potentially playing a part here, as well. Families don’t have as much disposable income and just aren’t going to go.
For families that are going to go, many may only go to one film all summer and adults aren’t go aren’t going to choose to pay that money for a film they may not enjoy. They’ll want to go see Top Gun, Jurassic World, Thor 4, etc - something that both the kids and adults can enjoy.